Mechanical bistable device

ABSTRACT

A snap acting, bistable, pushbutton operator or the like for actuating any apparatus requiring a mechanical movement including, but not limited to, an electrical switch. A spring is used to bias the pushbutton. The same said spring also produces the actuating movement. The spring also provides the snap action, and establishes the bistable character of the operator. The spring can also be conductive and can act, for example, as the pole of a single-pole, double-throw switch. The spring itself may be simply a rectangular strip, i.e., a spring metal leaf or otherwise. Thus, even though it can be very simple in construction, it can faithfully perform an unexpectedly large number of functions. The operator is thus relatively simple in construction because of, for example, the use of the single selfsame spring to perform a plurality of relatively complex functions.

United States Patent Wolf MECHANICAL BISTABLE DEVICE Inventor: Heribert Wolf. Nurnberg, Germany International Standard Electric Corporation, New York, NY.

Filed: June 8, 1973 Appl. No.: 368,187

Assignee:

Foreign Application Priority Data June 20, 1972 Germany 2230028 US. Cl 267/159, 200/67 DB Int. Cl. .j. F16f 1/18 Field of Search 267/l58 V, 159 V;

ll/l956 Foster .i 267/l58 6/197] 'l'wytord 267/159 Primary Iixumirwr-Jamcs B. Marbert [57] ABSTRACT A snap acting, bistable, pushbutton operator or the like for actuating any apparatus requiring a mechanical movement including, but not limited to, an electrical switch. A spring is used to bias the pushbutton. The same said spring also produces the actuating movement. The spring also provides the snap action, and establishes the bistable character of the operator. The spring can also be conductive and can act, for example, .as the pole of a single-pole, double-throw switch. The spring itself may be simply a rectangular strip, i.e., a spring metal leaf or otherwise. Thus, even though it can be very simple in construction, it can faithfully perform an unexpectedly large number of functions. The operator is thus relatively simple in construction because of, for example, the use of the single selfsame spring to perform a plurality of relatively complex functions.

11 Claims, 11 Drawing Figures PATENTEUHARZSBYS 3,873,078

sum 1 [IF 4 'mu ,5 I w Fig.2

, 1 MECHANICAL BISTABLE DEVICE BACKGROUND OF THE INVENTION This invention relates to mechanical operators for any apparatus requiring a mechanical actuating movement, and more particularly, to a snap acting, bistable actuator.

1n the past, the construction of snap acting, bistable operators including, but not limited to, toggle switches have been relatively complicated and expensive because several parts have been required to perform several functions required thereof.

SUMMARY OF THE INVENTION In accordance with the device of the present invention, the above-described and other disadvantages of the prior art are overcome by providing a snap acting, bistable operator for actuation of apparatus by the production of a mechanical movement.

The present invention may or may not have any one or more or all of the following features, as desired.

A spring may be employed to bias a pushbutton or actuating member. i

The selfsame spring'can also provide the snap action. The selfsame spring can also establish the bistable character of the device of the present invention.

The selfsame spring can be conductive and can act,

for example, as the pole of a single-pole, double-throw BRIEF DESCRIPTION OF THE DRAWINGS In the drawings which are to be regarded as merely illustrative:

FIG. 1 is a side elevational view, partly in section, of a partially disassembled snap acting device constructed in accordance with the present invention;

FIG. 2is a vertical sectional view of the snap acting device of FIG. 1;

FIG. 3 is a perspective view of a portion of an alternative embodiment of the present invention;

FIG. 4 is a side elevational view, partly in section, of a single-pole, double-throwswitch constructed in accordance with the present invention;

Fig. 5 is a perspective view of a fourth alternative embodiment of the present invention; and

FIGS. 6to 11, inclusive, are positional views illustrating how the parts of the snap acting device of the present invention move during operation thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT In thedrawings, in Figs. 1 and 2, a snap acting device isshown including a body 10', a pushbutton 70, a slide 50 and a flat spring 60.

Inside the body 10' there is a somewhat heart-shaped flat recess with right-hand and left-hand sidewalls and 30 thereof that has a depth greater than the width of the flat spring 60, if desired. The flat spring 60 is arranged inside this recess with almost two thirds of its length below a slot in Fig. 2. The lower end of spring 60 abuts a corner or point 40 of the recess. The other end of the spring 60 is supported at 80 in the pushbutton 70.

The pushbutton 70 is guided for movement relative to body 10' by being fixed relative to the upper end of slide 50. Slide 50 is slidably guided in aguide groove of the body 10'. Two limit stops 5a and 5b, in the positions thereof shown in FIG. 1, engage shoulders 10a and 10b of the guide groove 100 to limit upward movement of slide 50 and pushbutton 70, as viewed in FIG. 1.

The body 10 with its heart-shaped recess is covered by the plate 110.

From FIG. 3, it will be seen that an-L-shaped member may be employed, if desired, and may, if desired, be slidably mounted in a slot identical to slot 90 of FIG. 2. With the aid of member 120, a photoelectric switch may be actuated, if desired.

An embodiment is shown in FIG. 4 in which a flat spring60" carries a contact 130. Contacts are also provided at Ma and 14b. In this embodiment care preferably is taken to make contact sufficiently large so that the contact 130 will remain in engagement with one of the fixed contacts until the spring 60"rapidly snaps to a position similar to that shown in FIG. 6. It has proved advantageous to provide for a frictional engagement between contacts. Among other advantages therof, self-cleaning of the contacts is effected. Improved positive contact engagement can be achieved by constructing the body in a mannersuch that the lower end of spring 60" is fixed relative to the body and fixed in a slot 40' in the body.

FIG. 5 shows a further example for using the snap acting mechanism in connection with a rotary switch. In this case, a spring 60 is firmly connected to a rotatably support bolt or shaft l50. To this bolt there may be mounted, for example, a conductive disc 160. In this embodiment, however, the spring in its normal position preferably is bent to such an extent that it engages sidewalls similar to sidewalls 20 and 30 shown in FIG. 1. In this way, it is possible to prevent bolt from twisting prior to the actual snap over.

From FIGS. 6-11, it can be seen how the parts move. In FIG. 6, a spring 60"" is slightly curved and engages a projection 2a of a limiting stop wall 20'. Upon moving the pushbutton in a direction towards 40" the spring 60"" approximately and more nearly conforms to the shape of the limiting stop wall 20' as shown'in FIG. 7. The upperpart of the spring 60"",as shown in FIG. 7, has a curvature which is the reverse of its curvature that is shown in FIG. 6. Further depression of the pushbutton causes the curvature'of spring 60"" to change from that shown in FIG. 7 to that shown FIG. 8, i.e. to a more or less figure-S shape.

The condition of the spring prior to the snap overis shown in FIG. 9. FIG. 10 shows the condition of the spring after the snap over. If, in this condition of the spring, the pushbutton is depressed further, the spring 60"" will bear against one of two limiting stop walls 20 and 30' without being permitted to snap back over again in the reverse direction. Upon releasing the pushbutton, the spring 60"" is permitted to relax, and will 3 thereafter remain in one of the postitions illustrated in FIGS. 6 and 11.

In FIGS. 6 to 11, inclusive, relative to the snap action, it is preferable for the two limit stops 2a and 3a of the limiting stop walls and to be arranged far enough apart from each other so that the upper bend of the spring can freely increase until a snap of the spring is effected.

With respect to the embodiment shown in FIGS. 1 and 2, the following dimensions are preferred and some have advantages:

1. The spacing between 80 and in FIG. 1 preferably is about 30 millimeters.

2. The spacing between the two limit stops the same as or similar to limit stops 14a and 14b in FIG. 4 is about 6 millimeters.

3. The largest spacing between the two opposite points of the heart-shaped curve is preferably 10 millimeters.

4. The spacing between the two limit stops the same as or similar to limit stops 14a and 14b in FIG. 4 at the rim portion of the opening of the heart-shaped curve in relation to the same location or that similar to the location of 40' is preferably 18 millimeters.

A flat or leaf spring can be usefully employed in accordance with the present invention, and the use thereof may be extremely advantageous; however, a spring wire or even a helical or other spring may be used for this purpose and some or all of the time results may be obtained which are as good as or better than results which are obtained by using a flat or leaf spring. For the proper functioning of the snap-acting device it can be important that the springs are limited or guided in their movements so that they can move in one plane only. The use of the limit stops can also be important.

According to the present invention, several snap acting devices of the kind described hereinbefore, may be integrated to form one building block. Thus, for example, four snap acting devices with four discs or L- shaped members may be combined to form one structural unit. i

What is claimed is:

l. A snap acting operator comprising: a housing having a recess therein; a movable member; motion direction means to'guide movement of said member, said member having a recess therein, said member recess extending toward and reaching a first apex pointing in a first predetermined direction, said housing recess extending toward and reaching a second apex pointing in a second predetermined direction opposite said first predetermined direction, said housing recess having a projection fixed relative thereto on each of two opposite sides of said housing recess in positions extending into said housing recess, said housing recess having sides receding in opposite directions away from said projections, respectively, on the side thereof opposite the side thereof on which said member is located; and a spring in said recesses having first and second opposite ends thereof adapted to fit into said first and second apexes, respectively, said spring being movable from a position in engagement with either one of said projections to a position in engagement with the other by movement of said member toward said housing, said housing having first and second spaced and parallel main flat surfaces partially defining said housing recess, said housing recess having surface portions defining the remainder of said housing recess, said surface portions being normal to said first and second main flat surfaces,

said surface portions lying in mathematical surfaces described by moving a first line segment in a direction normal thereto while located between said first and second main flat surfaces normal thereto and having first and second ends located in the respective first and second main flat surfaces, said housing recess and said member recess being symmetrical about a plane normal to said first and second main flat surfaces midway between said projections and passing through said apexes, two of said surface portions being first and second auxiliary flat surfaces which intersect substantially in a second line segment normal to said first and second main flat surfaces, which second line segment is effectively said second apex, said member having third and fourth main flat surfaces approximately in the planes of said respective first and second main flat surfaces, and partially defining said member recess, said member having third and fourth auxiliary flat surfaces normal to and extending between said third and fourth main flat surfaces, said third and fourth auxiliary flat surfaces intersecting substantially in a third line segment normal to said third and fourth main flat surfaces, which third line segment is effectively said first apex, said member and housing having flat facing sides with respective facing openings into the respective recesses therein, said spring being a straight metal leaf spring having a rectangular cross section uniform along its length, said spring being flat when unstressed, said motion direction means including a straight slot in said housing and having an opening through said facing end of said housing. said slot being symmetrical about a plane through said apexes and having a rectangular cross section uniform throughout a portion of its length thereinto from said opening thereinto, a straight rigid slide having a rectangular cross section uniform throughout its length fixed relative to said member and slidable in said slot, stop means fixed relative to said housing and engageable by said slide to limit movement of said slide in a direction out of said slot, said spring being column loaded between said housing and member apexes when said slide engages said stop means in a manner such that said spring takes a deflection so that it successively and substantially forms each one of both oppositely disposed arcs, said spring being movable to a first position engageable with one of said projections, movement of said spring from engagement with said one projection to a second position for engagement with the other being caused by a movement of said member toward housing, subsequent movement of said member to a position where said slide lies in engagement with said stop means making it possible to move said spring from said second position thereof to said first position thereof by again moving said member toward said housing, the transfer of said springfrom said first position thereof to said second position therof, and vice versa, being successively possible substantially ad infinitum, said spring being bistable, that is, stable in each of said first and second positions thereof, said member and housing recesses being of widths only slightly greater than said spring to guide movement of said spring, said projections being located about two-thirds the maximum distance between apexes from the apex in said housing recess, said apex in said housing recess having a groove therein in which the end of said spring is held in cantilever fashion, each projection having a conductive switch contact engageable by said spring when itis in its respective first and second positions.

2. The invention as defined in claim 1, wherein said spring includes a metal leaf spring.

3. The invention as defined in claim 2, wherein said spring is straight and has a uniform rectangular cross section along its length.

4. The invention as defined in claim 3, wherein said spring is flat when it is unstressed.

5. The invention as defined in claim l,'wherein said spring is movable to a first position engageable with one of said projections, movement of said spring from engagement with siad one projection to a second position for engagement with the other being caused by movement of said member toward said housing, subsequent movementof said member to a position where said member is spaced from said housing said predetermined distance making'it possible to move said spring from said second position thereof to said first position thereof by again moving said member toward said housing, the transfer of said spring from said first position thereof to said second position thereof and vice versa, being successively possible substantially ad infinitum, said spring being bistable, that is, stable in each of said first and second positions thereof.

6. The invention as defined in claim 5, wherein said spring includes a metal leaf spring.

7. The invention as defined in claim 6, wherein said spring is straight and has a uniform rectangular cross section along its length.

8. The invention as defined in claim 7, wherein said spring is flat when it is unstressed.

9. The invention as defined in claim 8, wherein said member and housing recesses are of widths greater than said spring to permit movement of said spring 10. A snap acting operator comprising: a housing having a recess therein: a movable member; motion direction means to guide movement of said member, said member having a recess therein, said member recess extending toward and reaching a first apex pointing in a first predetermined direction, said housing recess extending toward and reaching a second apex pointing in a second predetermined direction opposite said first predetermined direction,said housing recess having a projection fixed relative thereto on each of two opposite sides of said housing recess in positions extending into said housing recess, said housing recess having sides receding in opposite directions away from said projections, respectively, on the side thereof opposite the side thereof on which said member is located; and a spring in said recesses having first and second opposite ends thereof adapted to fit into said first and second apexes, respectively, said spring being movable from a position in engagement with either one of said projections to a position in engagement with the other by movement of said member toward said housing, said housing having first and second space and parallel main flat surfaces partially defining said housing recess, having surface portions defining the remainder of said housing recess, said recesses having a generally central plane passing through stop means fixed relative to said housing to prevent movement of said member beyond a predetermined distance away from said housing, said spring being column loaded when said member is spaced said predetermined distance away from said housing in a manner such that said spring takes a deflection so that it successively and substantially forms each one of both oppositely disposed arcs of said spring, said projections always being located closer to said member apex than to said housing apex.

11. A snap acting operator comprising: a housing having a recess therein; a movable member; motion direction means to guide movement of said member, said member having a recess therein, said member recess extending toward and reaching a first apex pointing in a first predetermined direction, said housing recess extending toward and reaching a second apex pointing in a second predetermined direction opposite said first predetermined direction, said housing recess having a projection fixed relative thereto on each of two opposite sides of said housing recess in positions extending into said housing recess, said housing recess having sides receding in opposite directions away from said projections, respectively, on the side thereof opposite the side thereof on which said member is located; and a spring in said recesses having first and second opposite ends thereof adapted to fit into said first and second apexes, respectively, said spring being movable from a position in engagement with either one of said projections to a position in engagement with the other by movement of said member toward said housing, said housing apex having a groove therein in which the end of said spring is held in cantilever fashion, each projection having a conductive switch contact engageable by said spring when it is in its respective first and second positions. 

1. A snap acting operator comprising: a housing having a recess therein; a movable member; motion direction means to guide movement of said member, said member having a recess therein, said member recess extending toward and reaching a first apex pointing in a first predetermined direction, said housing recess extending toward and reaching a second apex pointing in a second predetermined direction opposite said first predetermined direction, said housing recess having a projection fixed relative thereto on each of two opposite sides of said housing recess in positions extending into said housing recess, said housing recess having sides receding in opposite directions away from said projections, respectively, on the side thereof opposite the side thereof on which said member is located; and a spring in said recesses having first and second opposite ends thereof adapted to fit into said first and second apexes, respectively, said spring being movable from a position in engagement with either one of said projections to a position in engagement with the other by movement of said member toward said housing, said housing having first and second spaced and parallel main flat surfaces partially defining said housing recess, said housing recess having surface portions defining the remainder of said housing recess, said surface portions being normal to said first and second main flat surfaces, said surface portions lying in mathematical surfaces described by moving a first line segment in a direction normal thereto while located between said first and second main flat surfaces normal thereto and having first and second ends located in the respective first and second main flat surfaces, said housing recess and said member recess being symmetrical about a plane normal to said first and second main flat surfaces midway between said projections and passing through said apexes, two of said surface portions being first and second auxiliary flat surfaces which intersect substantially in a second line segment normaL to said first and second main flat surfaces, which second line segment is effectively said second apex, said member having third and fourth main flat surfaces approximately in the planes of said respective first and second main flat surfaces, and partially defining said member recess, said member having third and fourth auxiliary flat surfaces normal to and extending between said third and fourth main flat surfaces, said third and fourth auxiliary flat surfaces intersecting substantially in a third line segment normal to said third and fourth main flat surfaces, which third line segment is effectively said first apex, said member and housing having flat facing sides with respective facing openings into the respective recesses therein, said spring being a straight metal leaf spring having a rectangular cross section uniform along its length, said spring being flat when unstressed, said motion direction means including a straight slot in said housing and having an opening through said facing end of said housing, said slot being symmetrical about a plane through said apexes and having a rectangular cross section uniform throughout a portion of its length thereinto from said opening thereinto, a straight rigid slide having a rectangular cross section uniform throughout its length fixed relative to said member and slidable in said slot, stop means fixed relative to said housing and engageable by said slide to limit movement of said slide in a direction out of said slot, said spring being column loaded between said housing and member apexes when said slide engages said stop means in a manner such that said spring takes a deflection so that it successively and substantially forms each one of both oppositely disposed arcs, said spring being movable to a first position engageable with one of said projections, movement of said spring from engagement with said one projection to a second position for engagement with the other being caused by a movement of said member toward housing, subsequent movement of said member to a position where said slide lies in engagement with said stop means making it possible to move said spring from said second position thereof to said first position thereof by again moving said member toward said housing, the transfer of said spring from said first position thereof to said second position therof, and vice versa, being successively possible substantially ad infinitum, said spring being bistable, that is, stable in each of said first and second positions thereof, said member and housing recesses being of widths only slightly greater than said spring to guide movement of said spring, said projections being located about two-thirds the maximum distance between apexes from the apex in said housing recess, said apex in said housing recess having a groove therein in which the end of said spring is held in cantilever fashion, each projection having a conductive switch contact engageable by said spring when it is in its respective first and second positions.
 2. The invention as defined in claim 1, wherein said spring includes a metal leaf spring.
 3. The invention as defined in claim 2, wherein said spring is straight and has a uniform rectangular cross section along its length.
 4. The invention as defined in claim 3, wherein said spring is flat when it is unstressed.
 5. The invention as defined in claim 1, wherein said spring is movable to a first position engageable with one of said projections, movement of said spring from engagement with siad one projection to a second position for engagement with the other being caused by movement of said member toward said housing, subsequent movement of said member to a position where said member is spaced from said housing said predetermined distance making it possible to move said spring from said second position thereof to said first position thereof by again moving said member toward said housing, the transfer of said spring from said first position thereof to said second position thereof and vice versa, beiNg successively possible substantially ad infinitum, said spring being bistable, that is, stable in each of said first and second positions thereof.
 6. The invention as defined in claim 5, wherein said spring includes a metal leaf spring.
 7. The invention as defined in claim 6, wherein said spring is straight and has a uniform rectangular cross section along its length.
 8. The invention as defined in claim 7, wherein said spring is flat when it is unstressed.
 9. The invention as defined in claim 8, wherein said member and housing recesses are of widths greater than said spring to permit movement of said spring
 10. A snap acting operator comprising: a housing having a recess therein: a movable member; motion direction means to guide movement of said member, said member having a recess therein, said member recess extending toward and reaching a first apex pointing in a first predetermined direction, said housing recess extending toward and reaching a second apex pointing in a second predetermined direction opposite said first predetermined direction, said housing recess having a projection fixed relative thereto on each of two opposite sides of said housing recess in positions extending into said housing recess, said housing recess having sides receding in opposite directions away from said projections, respectively, on the side thereof opposite the side thereof on which said member is located; and a spring in said recesses having first and second opposite ends thereof adapted to fit into said first and second apexes, respectively, said spring being movable from a position in engagement with either one of said projections to a position in engagement with the other by movement of said member toward said housing, said housing having first and second space and parallel main flat surfaces partially defining said housing recess, having surface portions defining the remainder of said housing recess, said recesses having a generally central plane passing through stop means fixed relative to said housing to prevent movement of said member beyond a predetermined distance away from said housing, said spring being column loaded when said member is spaced said predetermined distance away from said housing in a manner such that said spring takes a deflection so that it successively and substantially forms each one of both oppositely disposed arcs of said spring, said projections always being located closer to said member apex than to said housing apex.
 11. A snap acting operator comprising: a housing having a recess therein; a movable member; motion direction means to guide movement of said member, said member having a recess therein, said member recess extending toward and reaching a first apex pointing in a first predetermined direction, said housing recess extending toward and reaching a second apex pointing in a second predetermined direction opposite said first predetermined direction, said housing recess having a projection fixed relative thereto on each of two opposite sides of said housing recess in positions extending into said housing recess, said housing recess having sides receding in opposite directions away from said projections, respectively, on the side thereof opposite the side thereof on which said member is located; and a spring in said recesses having first and second opposite ends thereof adapted to fit into said first and second apexes, respectively, said spring being movable from a position in engagement with either one of said projections to a position in engagement with the other by movement of said member toward said housing, said housing apex having a groove therein in which the end of said spring is held in cantilever fashion, each projection having a conductive switch contact engageable by said spring when it is in its respective first and second positions. 